WEEKDAY
Determine the Day of the Week

WEEKDAY, a MATLAB library which can determine the day of the week corresponding to a given date; for instance, the battle of Hastings, on 14 October 1066 (Julian Calendar!), was a Saturday.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

WEEKDAY is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version and a Python version.

Related Data and Programs:

CALENDAR_NYT, a FORTRAN90 library which shows the correspondence between dates and the New York Times volume and issue number;

CALENDAR_RD, a C++ program which computes the representation of a given date in a number of calendrical systems, by Edward Reingold, Nachum Dershowitz

CALPAK, a FORTRAN90 library which makes various calendar calculations;

DATES, a dataset directory which contains lists of dates in various calendar systems.

DOOMSDAY, a MATLAB library which is given the year, month and day of a date, and uses John Conway's doomsday algorithm to determine the corresponding day of the week.

TEST_VALUES, a MATLAB library which supplies test values of various mathematical functions.

weekday_test

Reference:

1. Lewis Carroll (Charles Dodgson),
   To Find the Day of the Week for Any Given Date,
   Nature, 31 March 1887.
2. Gary Meisters,
   Lewis Carroll's Day-of-the-Week Algorithm,
   Math Horizons,
   November 2002, pages 24-25.
3. Edward Reingold, Nachum Dershowitz,
   Calendrical Calculations: The Millennium Edition,
   Cambridge University Press, 2001,
   ISBN: 0-521-77752-6,
   LC: CE12.R45.
4. Edward Richards,
   Mapping Time, The Calendar and Its History,
   Oxford, 1999,
   ISBN: 0-19-850413-6,
   LC: CE11.R5.

Source Code:

• i4_modp.m returns the positive remainder when I is divided by J.
• i4_wrap.m forces an integer to lie between given limits by wrapping.
• jed_to_weekday.m computes the day of the week from a JED.
• jed_weekday_values.m returns weekday values for selected JED's.
• timestamp.m prints the current YMDHMS date as a time stamp.
• weekday_to_name_common.m returns the name of a Common weekday.
• weekday_values.m returns the day of the week for various dates.
• y_common_to_astronomical.m converts a Common year to an Astronomical year.
• ymd_to_s_common.m writes a Common YMD date into a string.
• ymd_to_weekday_common.m returns the weekday of a Common YMD date.
• ymdf_compare.m compares two YMDF dates.
• ymdf_to_jed_common.m converts a Common YMDF date to a JED.
• ymdf_to_jed_gregorian.m converts a Gregorian YMDF date to a JED.
• ymdf_to_jed_julian.m converts a Julian YMDF date to a JED.